Fluid actuated mercury piston pump



B. F. SCHMIDT FLUID ACTUATED MERCURY PISTON PUMP A ril 2s, 1959 4 Sheets-Sheet 1 Filed May 21, 1956 R m r m I B w g Q m April 28, 1959 Y B. F, SCHMIDT FLUID ACTUATED MERCURY PISTON PUMP Filed May 21, 1956 4 Sheets-Sheet 2 INVENTOR Bar 0m in F 5657:1752;

/ y/ BY y ATTORNEY B. F. SCHMIDT FLUID ACTUATED MERCURY PISTON PUMP April 28, 1959 4 Sheets-Sheet 4 Filed May 21, 1956 JI'IQZf Ila. 16'.

- INVENTOR Bemjamz'nl". 1505011272:

IN hr i MP1 1: a 1\\\\ Y ll \\\\\\\\h 0 ATTORNEY United States Patent FLUID ACTUATED MERCURY PISTON PUMP Benjamin F. Schmidt, Los Angeles, Calif.

Application May 21, 1956, Serial No. 586,042

11 Claims. (Cl. 103-44) This invention relates to an oil well pump of the fluid surge type embodying an expansible and contractile element filled with an operating fluid and including a reciprocal piston pump mechanism operable to effect surging of such liquid and thereby alternately expand and contract said element so that the latter, which is mounted and arranged so to do, will effect a pumping action on a liquid being pumped, and particularly pertains to a construction and arrangement in such a pump for sealing and protecting the pump mechanism from well liquid being pumped, all of the character set forth in my copending application, Serial Number 580,066, filed April 23, 1956 now Patent No. 2,814,993.

The primary object of the invention is to provide a pump of the above character which is double acting, that is, adapted to effect delivery of pumped liquid on both the up and down strokes of the pump piston which is accomplished by the provision of a pair of the expansile and contractile elements so mounted and arranged as to operate alternately in effecting their pumping operations; one of the elements expanding on down stroke of the piston and contracting on the upstroke thereof, while the other element expands on the upstroke of the piston and contracts on the downstroke thereof.

Another object is to provide a pump of the fluid surge closed circuit type in which an actuating piston pump element located in the pump structure is operatively connected at each end to the expansile and contractile elements by the actuating liquid.

Another object is to provide a construction whereby a piston rod packing gland and the working surfaces of actuating mechanism of the pump are prevented from being contacted by well liquid being pumped, through the medium of an entrapped body of lubricating oil arranged to submerge and surround all areas of the pump which ordinarily would be exposed to well liquid being pumped, and wherein the body of lubricating oil is held in place in the pump by an arrangement of telescoping tubes supplemented by a body of mercury confined by said tubes together with the body of lubricating oil.

A further object is to provide a construction in a pump of the above character whereby the parts thereof may be readily assembled, and whereby longitudinally aligned pump sections may be detachably joined with co-operating parts of the adjacent sections radially positioned in proper relation to each other.

With the foregoing objects in view together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the construction and arrangement of parts hereinafter described and claimed, and as illustrated by way of example in the accompanying drawings in which:

Fig. 1 is a view in section partly in elevation of the lower portion of the pump structure with portions removed and depicting the manner of interconnecting adjacent pump sections;

Fig. 2 is a view similar to Fig. 1 showing the upper portion of the pump structure;

'ice

Fig. 3 is a detail in horizontal section taken on the line 3-3 of Fig. 1;

Fig. 4 is a detail in horizontal section taken on the line 4-4 of Fig. 1;

Fig. 5 is a detail in horizontal section taken on the line 5-5 of Fig. 1;

Fig. 6 is an enlarged detail in vertical section taken on the line 6-6 of Fig. 1;

Fig. 7 is an inverted cross section taken on the line 77 of Fig .6;

Fig. 8 is a detail in horizontal section taken on the line 8-8 of Fig. 1;

Fig. 9 is a detail in horizontal section taken on the line 9-9 of Fig. 2;

Fig. 10 is a detail in horizontal section taken on the line 10-10 of Fig. 2;

Fig. 11 is a schematic view of the pump in vertical section partly in elevation disregarding proportions and oertain details of construction depicting the operation of the invention on upstroke of the pump piston;

Fig. 12 is a schematic view similar to Fig. 11 denoting the mode of operation of the pump on downstroke of the piston;

Fig. 13 is a schematic view in vertical section illustrating the manner of entrapping the pump piston in the body of actuating liquid and sealing the latter from contact with the liquid being pumped by an interposed body of mercury;

Figs. 14 and 15 are diagrams in vertical section of the lower and upper portions respectively of a modified form of the invention;

Fig. 16 is a cross section taken on the line 16-16 of Fig. 14; and

Fig. 17 is a section on line 17-17 of Fig. 15.

The pump structure as here shown embodies a lower section A and an upper section B having cylindrical pump tubes 15 and 16 respectively here shown as united by a coupling 17. The tube 15 is connected at its lower end by a coupling 18 to a tube 19 adapted to be positioned in the lower end portion of a well casing in the usual manner. The upper end of the pump tube 16 is connected in the usual fashion to a string of tubing (not shown) leading from the well to discharge.

In carrying out the invention the lower pump tube 15 is divided into longitudinal chambers 20-21 by a diametrically extending rigid partition 22 the side margins of which tightly abut and are secured to the inner face of the tube 15. The partition 22 leads between the upper and lower ends of the tube 15, which ends constitute respectively transverse cylindrical walls 23 and 24 of which the lower end wall 24 is brazed to the lower end of the tube 15. The upper end wall 23 bears on the upper end of the partition 22 and seats throughout its margin on a shoulder a formed on the upper inner end portion of the tube 15, a gasket b being interposed between the contiguous surfaces of the end wall 23 and the shoulder a and partition 22. The end wall 23 is detachably secured in place by a bolt 0 passed axially through the wall 23 and screwed into engagement with the adjacent end of the partition 22.

The wall 23 overlies the upper end of the tube 15 and is formed with a reduced concentric cylindrical upper portion d bordered by a fiat upper faced flange e, which portion d projects into and through a space encompassed by an annular rib 1 formed interiorly of and intermediate the ends of the coupling 17 with the flange e and rib f abutting.

A pair of intake ports 25-26 (see Fig. 8) lead through the lower end wall 24 from the lower ends of the pump chamber 20-21 respectively, which ports open to intake passages 27 in a valve housing 19' telescoped in the coupling 18 and extending between the upper end of the [9 tube '19'and the wall 24, and which passages 27 are fitted with upwardly opening foot valves 28.

The chambers 2021 are provided at their lower ends with discharge ports 29 and 30 formed in the end vwall 24 as particularly shown in Fig. 8, which ports open to passages 31--32 in the housing 19' connecting with a discharge passage 33 leading-upwardly through the end wall 24 and along one marginal portion of the partition 22, the passages 3132being equipped with downwardly opening spring pressed check valves 34-35. The discharge passage 33 leads through the end wall 23 and opens to the interior of the lower end portion of the tube 16 adjacent the inner periphery of the latter through a passage 35 formed in a cylindrical foot piece 36 and an associated underlying disk 36 imposed on the end ,well 23. The foot piece 36 is encompassed and engaged by the lower end portion of the tube 16 and is formed with a marginal flange g which abuts the lower end of the tube 16. The lower portion of the foot piece '36 telescopically extends into the coupling 17 and is sealed relative thereto by a sealing ring it. The disk 36 seats at its margin on the flange f of the coupling 17 and is detachably connected to the end wall 23 by a bolt i which passes through the disk 36' and is screwed into engagement with the end wall 23 in alignment with the bolt 0.

The chambers 2021 respectively are equipped with expansile and contractile elements C and D here shown as comprising flexible walled bladders. The bladder ClSffilled with'a-bodyE of actuating fluid and the bladder 19 is-filled-with a body-F of actuating fluid. "The upper ends of the bladders CD are connected respectively to nipples 137- 38 which open to the interiors of the bladders and lead through the end wall 23, the nipples being fastened to and carried by said wall.

The foot piece 36 is formed with a central upwardly opening cylindrical chamber 39 from which leads an'upwardly extending pump cylinder 40 in which is reciprocally mounted a piston G fitted with a piston rod H leading upwardly through the pump tubing to a suitable actuating mechanism whereby the piston may be reciprocated in the conventional fashion.

The foot piece 36 and disk 36 are formed with a passage 41 which leads from the bottom of the chamber '39 and opens to the upper end of the nipple 37, the chamber "39, passage .41, and nipple 37 being filled with actuating fluidin continuation of thebody E thereof contained in the element C.

The cylinder 40 extends above th upper end of the piston G when the latter is in its uppermost position as indicatedin Fig. 12 and is fitted with an end wall 40' fitted with a gland jthrough which the piston rod H slidably and sealingly extends. Formed in the upper end portion of the cylinder 40 immediately below the end wall 40' are apertures 41 which lead to a space k surrounding the cylinder 40 and enclosed by a fixed cylinder 43 encompassing the cylinder 40 in spaced relation thereto which cylinder 43 is afiixed at its lower end to the foot piece 36 and has its upper end fixed to and closed by the end wall 40 at the upper end of the cylinder .40. The-Space k opens at its lower end to a passage 44 in the foot piece 36 which leads through the disk 36' and opens to the upper end of the nipple 38. The space in the cylinder40 above the piston G together with the spacek, passage44, and nipple 38 are filled with a continuation of the body F of actuating fluid contained in the e ement D.

Encompassing the cylinder 43 in spaced relation thereto and spaced inwardly from the inner periphery of the tube 16 is an upstanding cylindrical sleeve 45 carried on and sealed relative to the foot piece 36. The upper end of the sleeve .45 terminates adjacent the upper end of the cylinder 40 and opens to the interior of the tube 16.

Fixed on the pump rod H by a grip l in suitable upwardly spaced relation to the wall 40 is a disk 46 on which is fixed a dependent cylindrical sleeve 47 which extends downwardly between the cylinders 43 and 45 intermediate thereof and terminates at its lower end in suitable spaced relation to the upper end of the foot piece 36 as particularly shown in Fig. 13, which sleeve 47 travels with the pump rod H. A body of lubricating oil I is interposed between and the major portion of the space m between the cylinder 43 and the sleeve 47. Disposed in the space nbetween the sleeve 47 and the cylinder 43 is a body K of mercury which extends upwardly a suitable distance into the interior of the lower end portion of the sleeve 47 and meets the oil body I in the latter.

The mercury body K extends up into the space n to a point spaced a requisite distance below the upper open end of the sleeve 45 where it meets the body of liquid being pumped contained in the pump tube. The surfaces of the sleeve 4345 and 47 contacted by the mercury body K are .silvered in any suitable manner.

The pump rod H is equipped at a point spaced above thejdisk 46 with an apertured disk 48 which loosely contacts the inner periphery of the pump tube 16 and serves as a guide for the pump rod H and affixed interiorly of the pump tube 16 in upwardly spaced relation to the disk 48.is a ring 49 which is adapted to be engaged by the. disk 48 on upward movement of the pump rod to a point slightly above the termination of its upward stroke so that the pump rod H may be utilized as a support for the pump tube string in elfecting its lowering into a well casing and its withdrawal therefrom.

In the operation of the invention, assuming that the pump piston G is in its lowermost position wherein the actuating fluid E below the piston is under pressure and has thereby fully dilated the element C and wherein the actuating fluid F extending from above the piston G and the interior of the element D has effected contraction of theilatter, as shown in Fig. 5, upstroke of the piston G effects displacement of the fluid F and dilates the element D so as to effect discharge of previously intaken liquid being pumped in thechamber 21 which pumped liquid will then be discharged through the valved outlet 30 upwardly through the passage 33 into the upper pump tubing 16 for eventual discharge. The upwardly moving pistontheninduces the actuating fluid from the element C thereby effecting contraction of the latter so as to induct liquid from the well into the pump chamber 20 through the valved intake 27 so as to charge the pump chamber 21 with the well fluid.

Downstroke of the piston G reverses the operation in obvious fashion.

from the foregoing it will be seen that by alternating thecontraction and expansion of the elements CD the pump is rendered double acting in that fluid being pumped will be directed to discharge on both the up and down stroke of the piston.

A feature of the invention resides in the construction whereby the pump section A-B may be assembled with the respective parts thereof in proper relation to each other, it being essential that the passages leading from the sections A bedisposed in register with their companion passages in the section B. This is accomplished by the provision in the threaded coupling 17 of the telescoping parts 23-36 and 36 which are positionable in register With each other independent of the threaded interconnectionof the coupling 17 and the tube sections 15 and 16.

In assembling this portion of the structure and uniting the sections A.B, the end wall 23 is initially clamped in place on the upper end of the tube 21 by the bolt'c with the bladders CD attached thereto and disposed in their respective chambers 2021 on opposite sides of the partition ,22. The coupling 17 is then screwed in place on the upper end .of the tube 16 to bring the internal rib 1 thereof into abutting relation to the shoulder e of the wall 23.

The disk '36 is then telescoped in the coupling 17 and positioned over the wall 23 and rib f with the several passages therein in register with their companion passages in the wall 23 the disk 36 being then secured in place by the bolt i. The foot piece 36 is then telescoped in the coupling 17 and seated on the disk 36' with the passages therein in register with their companion passages in the latter.

The element C, together with the passages 37-41 and the chamber 39 are then filled with the body E of actuating fluid whereupon the piston cylinder 40 with the piston G disposed therein and positioned at the lower end thereof is screwed in place in the foot piece 36 so that the piston will bear on the actuating fluid when in its lowermost position and thereby dilate the element C.

The cylinder 43 and the sleeve 45 are then applied to the foot piece 36. The tube section 16 is finally screwed into the coupling 17 to bear on the foot piece 36 and clamp it against the disk 36'.

In like fashion the valve block 19' is telescoped in the coupling 18 after attachment of the latter to the tube 15 and positioned with the valve chambers therein in register with the ports 25-26 and 29-30 in the end wall 24 and with the passage 31 in register with the discharge passage 33. The tube section 19 is then screwed into engagement with the coupling 18 to clamp the valve block in place against the underside of the wall 24.

On assembling the piston cylinder 40 and cylinder 43 on the foot piece 36 with the end wall 40' and packing gland j applied, the piston G is disposed in the cylinder 40 near its uppermost position whereupon the body F of actuating fluid is applied to fill the element D and the passage 38-44 and space k extending between the latter and the piston, such fluid being delivered through a filler opening p in the end wall 40 which is subsequently closed by a plug q.

On assembling the sleeve 47 on the piston rod H, a measured quantity of the mercury body K is delivered into the space m through a filler opening r in the end wall 46 such as to establish a predetermined level of mercury in the lower end portion of the space m and to submerge the lower end of the sleeve 47 when in its uppermost position. The space m above the mercury body therein is then filled with the body I of lubricating oil whereupon and after forming the mercury column K in the space n by feeding mercury into the open upper end of the cyl inder 45, the filler opening r is closed by a plug .5.

In the modified form of the invention shown in Figs. 14 to 17 inclusive, the pair of expansible and contractile elements, indicated at D and C' are arranged in tandem in longitudinally spaced pump chambers 50-51 in axially aligned pump tube sections 52-53 instead of being disposed in parallel relation to each other in a divided single pump tube as shown in Figs. 5, 6 and 7 and as above described. As depicted in Fig. 14 the pump tube 52 containing the element D is fitted at its lower end with an intake portion 54 and a valve housing 55 which latter is formed with a passage 56 leading to the pump chamber 50 and having an intake port 57 fitted with a foot valve 57; the housing 55 also being formed with a discharge passage 58 leading from the passage 56 to an upstanding discharge conduit 59 and being fitted with a normally closed upwardly opening foot valve 58.

The conduit 59 leads to and connects with a passage 60 leading through a header 61 carried on the upper end of the pump tube 52 which passage connects with a discharge conduit in the tube 53 as later described. The header 61 carries a nipple 62 extending therethrough and having its lower end afiixed to and opening to the interior of the element D.

The lower end of the pump tube 53 is fitted with a valve housing 64 formed with a passage 65 leading from the chamber 51 and having an intake port 66 fitted with an upwardly opening foot valve 67; the housing 64 also being provided with a discharge passage 68 leading from the passage 65 .and fitted with an upwardly opening foot valve 69. The port 66 opens to an inlet passage 70 in a coupling block 71 which passage opens at its outer end to the exterior of the pump for ingress of well liquid being pumped. The passage 68 leads to a discharge conduit 72 extending upward in the pump tube 53.

The coupling block 71 is formed with a passage 73 having a lower end opening to the nipple 62 and having its upper end connecting with a passage 74 leading through the housing 64 and connecting with the lower end of a conduit 75 (see Fig. 17) leading upward in the pump tube 53 for subsequent connection to a surge pump. A third conduit 76 constituting a discharge conduit, leads longitudinally of the pump tube 53 intermediate the conduits 72-75, the lower end of which conduit 76 connects through the housing 64 and coupling block 71, by a passage 77 (indicated in dotted lines in Fig. 14) with the passage 60 at the upper end of the discharge pipe 59.

The upper end of the pump tube 53 is fitted with a header 78 having a nipple 79 leading therethrough and connecting with and opening to the element C and which header is formed with a passage 80 with which is connected the upper end of the conduit 75 opening to the element D through the passages 74-73 and nipple 62. The header 78 is also formed with a passage 81 with which the upper end of the discharge conduit 76 connects.

Attached to the upper end of the pump tube 15" is a pump section B corresponding to the section B previously described, the passage 44 in the lower end of which communicates with the nipple 79 thus affording communication between the element C' and the upper end of the piston cylinder 40, while the lower end of the piston cylinder 40 communicates with the passage 81 and conduit 75 connecting with the upper end of the element D. The discharge passage 35 of the section B communicates with the upper ends of the discharge conduits 72 and 76 where they open through the header 78.

The elements C and D and their respective communications leading to the upper and lower ends of the pump piston G are filled with an actuating liquid which is surged back and forth on reciprocation of the piston to cause alternate contraction and dilation of the elements C and D to cause them to effect their respective pumping actions in the manner above set forth.

I claim:

1. In an oil well pump of the surge type, an upper section of pump tube, a foot piece on the lower end of said tube, an axially extending pump cylinder extending upwardly from said foot piece concentric with said tube, a piston in said cylinder, a cylindrical shell carried on said foot piece in outward spaced concentric relation to said piston cylinder having a closed upper end, said pump cylinder being formed with apertures in its upper end portion communicating with the space between said cylinder and shell, an upstanding cylindrical shell carried on said foot piece interposed between said outer cylinder and the inner periphery of said pump tube in concentric spaced relation to said shell and tube, said shell having its upper end opening to the interior of said pump tube, a piston rod connected to said piston leading into and sealed from the upper end of said piston cylinder, a cylindrical sleeve carried by said piston rod above said pump cylinder closed at its upper end, said sleeve leading downwardly concentrically and intermediate said outer sleeve and said shell and spaced from each, a body of lubricating oil entrapped in said last named sleeve and encompassing the upper portion of said cylindrical sleeve, a body of mercury entrapped in said first named sleeve extending upwardly into the lower end portion of said shell, said pump embodying a lower tube section having a valved inlet and a valved outlet, said outlet having a fluid connection with the space between the upper pump tube and the adjacent shell, and a pair of tubular expansile and contractile elements in said lower pump tube, the upper end of one of said tubular elements communicating with the interior of said piston cylinder beneath said piston, the upper end of the other of said tubular elements having fluid communication with the interior of the space between said pump cylinder and its encompassing cylinder, and bodies of activating fluid filling said tubular elements and leading to the ends of said piston, said bodies of liquid being responsive to reciprocation of said piston to effect alternate expansion and contraction of said elements.

2. The structure called for in claim 1 together with a coupling interconnecting said upper and lower pump tubes, a transverse wall intermediate the ends of said coupling abutting the under side of the foot piece on the upper tube, and a partition leading from the under side of said wall axially of said lower tube throughout the length thereof dividing said lower pump tube into separated chambers in which said expansile and contractile elements are separately arranged, and the lower ends of each of said chambers being provided with complementary pairs of said valved inlets and outlets.

3. In an oil well pump of the surge type, a lower pump section embodying a vertical tube, couplings attached to the upper and lower ends of said tube each of which is fitted with a transverse wall intermediate its ends forming said tube with upper and lower end walls, a partition extending between said end walls and diametrically across said tube forming the latter with separated longitudinal chambers, said lower end wall being formed with an inlet port and an outlet port lead ing from each of said chambers, a valve housing in the lowermost of said couplings having a pair of valved inlet passages leading to said inlet ports and having a pair of valved outlet passages leading from said outlet ports, a discharge passage connected with said outlet ports leading along said partition through said upper end wall, an expansile and contractile element in each of said chambers containing bodies of operating liquid, and reciprocal means connected to the upper of said couplings for surging said liquid bodies to eflect alternate expansion and contraction of said elements.

4. The structure called for in claim 3 together with a second pump tube leading from the coupling at the upper .end of the first named pump tube, said discharge passage opening to said second tube, said reciprocal means being housed in said second tube and being encompassed by said operating liquid.

5. In a seal for protecting submerged fluid seal pumping mechanism from being contaminated by fluid being pumped by said mechanism, a pumping mechanism, a reciprocal element embodied in said pumping mechanism, a tubular sleeve attached to and surrounding a portion of said pumping mechanism in spaced relation thereto, a body of lubricating oil and a body of mercury in said sleeve, a second sleeve aflixed to said reciprocating element, said second sleeve extending downwardly into said bodies of lubricating oil and mercury.

6. In a seal for protecting submerged fluid surge pumping .mechanism from being contaminated by fluid being pumped by said mechanism, said pump mechanism embodying a piston, a cylinder in which said piston is reciprocally mounted having working chambers above and below said piston, bodies of operating lubricating oil filling said chambers and contacting the surfaces of said piston and adapted to flow in and out of said cham bers on reciprocation of said piston for reciprocating same; a sleeve attached and sealed relative to said cylinder in spaced surrounding relation thereto, bodies of lubricating oil and mercury within said sleeve, and a second sleeve attached and sealed to said pump rod encompassing same in spaced relation thereto and extending over and around said pump cylinder and into the bodies of lubricating oil and mercury contained in said first named sleeve, and a body of lubricating oil in said second named sleeve above the mercury therein.

7. In a double acting oil well pump, a pair of laterally contractible and expandible hollow elements each containing a quantity of operating fluid housed, each of said elements being mounted within a chamber fitted with intake and discharge valves for crude oil, and a reciprocating mechanism attached at one end of said chambers having a piston arranged within a tubular member and having operating oil on each end of said piston, and fluid flow connections between the two bodies of operating oil in said reciprocating mechanism and the operating oil in each of said hollow expandible elements, and means connected to said piston to reciprocate same and cause said expandible element to contract and expand and produce a pumping action in said valved chambers, and a protective body of sealing lubricating oil encompassing said reciprocating mechanism and held in protective relation therewith by a plurality of attached tubular members encompassing said reciprocating mechanism, said tubular member containing a quantity of sealing oil and mercury and arranged to hold the oil and mercury in yieldable protective sealed relation with said reciprocating mechanism.

8. In a double acting oil well pump of the surge type embodying upper and lower pump tubes, a coupling joining said tubes having threaded connections therewith, said lower tube having a pair of vertically extending chambers each of which is fitted with a valved inlet and a valved outlet, an expansile and contractile tubular element in each of said chambers, said upper tube being fitted with a pump embodying a pump cylinder and a reciprocal piston in said cylinder, said cylinder having a combined fluid intake and outlet passage in each end thereof; said coupling having an internal flange inter mediate its ends, an upper end wall telescopically engaged by said lower tube and having an upper end portion encompassed by said flange, said end wall having a pair of passages opening to said expansile and con-' tractile elements, a disk telescoped in said coupling seated on said flange and on said end wall, said disk being formed with a pair of apertures registering with said passages, means detachably interconnecting said lower tube, end wall and disk together axially thereof, a foot piece telescopically engaged by said coupling and by said upper tube and seated on said disk having a pair of passages opening to said apertures, one of which communicates with the passage at one end of the piston cylinder and the other of which communicates with the passage at the other end of said cylinder; said upper tube having a pump chamber, and a discharge passage leading from said valved outlet and communicating with said upper pump chamber through said lower section, coupling, disk and foot piece.

9. In a double acting surge type pump, a pair of pump chambers each having a valved inlet and a valved outlet, a tubular expansile and contractile element in each of said chambers, a cylinder, a reciprocal piston in said cylinder, means confining an actuating fluid between the opposite ends of said piston and said elements with the fluid filling the latter and with the fluid in one of said elements extending to one end of the piston and the fluid in the other element leading to the other end of the pis-' ton, a piston rod leading from said piston, a packing gland carried by said cylinder through which said piston rod extends, an entrapped lubricating oil seal submerging the exterior of said gland, and a confined mercury body shielding said oil seal from liquid being pumped.

10. In a double acting oil well pump, a plurality of pump chambers arranged one above the other each of which is fitted with intake and discharge valves, a laterally expansile and contractile element in each of said chambers, fluid surge mechanism, each of said elements having fluid flow connections with said fluid surge mechanism in sealed relation therewith and arranged to flow operating fluid in and out of each of said elements to effect a pumping action in each of said pump chambers upon the, operation of fluid surge mechanism, said fluid surge mechanism embodying a plurality of fluid tight attached 9 and silver plated tubular sleeves containing oil and mercury bodies arranged around said fluid surge mechanism in such manner and fashion as to prevent pumped fluid from contacting any of the sealing or operating surfaces of said surge mechanism.

11. In an oil well pump of the fluid surge type embodying a lower pump section and an upper pump section operatively connected together, said lower pump section being provided with a pair of separated pump chambers each having lower ends fitted with a valved intake and a valved outlet, a discharge passage leading from said valved outlet to the interior of the pump section and thence to discharge; and expansile and contractile element in each of said chambers, a body of actuating liquid in each of said elements, each of said elements being adapted on contraction thereof to induct liquid being pumped, means in said upper section for surging the liquid back and forth in said elements to effect alternate expansion and contraction thereof and consequent alternate intake and discharge of pump fluid to and from said pumping chambers; said last named means embodying a pump cylinder in said upper section, a reciprocal piston in said cylinder, a piston rod for reciprocating said piston, and fluid connections whereby the body of actuating liquid in one of said elements is extended into said cylinder beneath said piston and whereby the actuating fluid in the other element is extended into the cylinder above said piston, said connections embodying a fixed cylinder encompassing said pump cylinder in spaced rela- 10 tion thereto having a closed upper end and opening at its upper end portion to the interior of the upper portion of said pump cylinder and having its lower end communicating with the interior of one of said elements, an upstanding cylindrical shell interposed between said last named cylinder and the inner periphery of the upper pump tube, said shell being concentrically spaced from said cylinder and said shell and having its interior in communication at the upper end thereof with the interior of said shell, a cylindrical sleeve extending between said shell and said adjacent cylinder in spaced relation thereto having the interior of its lower end communicating with the space between said shell and said cylinder and having its upper end closed and carried by said piston rod, a body of lubricating oil confined within said last named shell, and a body of mercury confined in said upstanding sleeve and extending into the lower portion of said shell.

References Cited in the file of this patent UNITED STATES PATENTS 1,782,144 Jensen Nov. 18, 1930 1,851,666 Evans Mar. 29, 1932 2,357,872 Bousman Sept. 12, 1944 2,489,505 Schmidt Nov. 29, 1949 2,606,500 Schmidt Aug. 12, 1952 FOREIGN PATENTS 12,090 Great Britain July 4, 1900 

